1. Field of the Invention
This invention relates generally to rolling mills, and is concerned in particular with the provision of an improved modular finishing mill for rolling long products such as rods, bars and the like.
2. Description of the Prior Art
With reference to FIG. 5A, a known modular finishing mill of the type described in U.S. Pat. No. 5,595,083 (Shore) comprises a plurality of rolling units R1-R5 arranged sequentially on a mill pass line P along which products are rolled in a rolling direction indicated by arrow 10. Gear units A1-A4 are arranged along a line L parallel to the mill pass line. The gear units are driven individually by motors M1-M4 and are offset with respect to the rolling units in the rolling direction. A continuous drive train is provided by connecting each gear unit to two successive rolling units.
Typically, when rolling smaller product sizes, e.g., rods with diameters of 5.0-6.5 mm, all rolling units R1-R5 are employed, at finishing speeds of up to 120 m/s and at tonnage rates of 70-90 tons/hr. In this case, the mill benefits from the power provided by all of the motors M1-M4 acting through the continuous drive train provided by the coupling of each gear unit to two successive rolling units. However, when rolling larger product sizes, at lower speeds and at higher tonnage rates on the order of 150 tons/hr, one or more of the rolling units at the exit end of the mill are typically removed from the pass line. If two rolling units are removed, as shown in FIG. 5B, the last motor M4 is in effect decoupled from the continuous drive train, thus reducing the power available to drive the mill at a time when the demand for power has increased as a result of the higher tonnage rates being produced. In order to compensate for such power deficiencies, the mills are equipped with larger motors, which disadvantageously increases the overall cost of the mill.
In the above described mill, the rolling units R1-R5 each comprise two oppositely inclined roll pairs. This design is unique to the modular mill concept, and is not readily adaptable for use at other mill locations, for example in post finishing mills of the type described in U.S. Pat. No. 5,325,697 (Shore et al.).